Uranus and Neptune

So I had a thought about Uranus and Neptune. Since Jupiter and Saturn are gas giants, ie mostly Hydrogren and Helium, their future might be as red dwarfs if we wished to expand the habitable zones of our solar system. (If red dwarfs have habitable zones.)

But Uranus and Neptune are different in that they are really ice giants. Neptune eg, is thought to have a rocky core, with a huge mantle of water ice, ammonia and methane, and then a large atmosphere of Hydrogen, Helium and methane. Temperatures in the mantle are estimated at 2,000 to 5,000 K. So it would seem to me that going the route of the Red dwarf might not be the best use of these ice giants. But instead could we go the other direction and make them super Earths?

Remove the atmosphere, about 1 Earth in mass of Hydrogen, Helium, and methane. Extract any deuterium or He3 for fusion, and the rest just dump into the gas giants for the eventual red dwarf stage. The methane could be used for other things, either striped of the hydrogen for the above mentioned uses. Also a small amount to merge with oxygen to make a CO2 for plant growth, or plastics manufacturing, etc.

Eventually as the atmosphere is reduced, methane and ammonia would de-gas replace the previous atmosphere and then you start removing them as well. Same thing, you can strip out the hydrogen to mine for deuterium, or leave ammonia as is for fertilizer throughout the solar systems farms, or strip out some for a nitrogen atmosphere (for the ice giant, Mars, and for buffer gas of space habitats, etc.)

Now you're left with a warm mostly water super Earth. The question being will it remain warm enough? Still at probably 9 Earths, I would expect it still to be pretty active geologically. Of course sunlight would still be very very low and would need to be considered. Will the pressure and gravity be suitable for life much less human life? The pressure can be managed by the final gravity and how much 'atmosphere' we leave there. Currently the 'surface' gives 1.19 G's, due to the large radius vs. its mass. So though we would be removing mass would also likely be decreasing radius. Not sure what the end gravity would be but considering most of the mass is still water which is less dense then the rocky core. I wouldn't think it would rise beyond what humans could manage. Lastly since we are playing solar system engineering anyway, if it was still too cold we might consider moving the new super Earths closer to a future Saturn red giant. Not sure how the orbital mechanics would work for actually getting them captured but just an idea.
Brooks